package com.yangluyao.test.ABA;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.atomic.AtomicStampedReference;

/**
 * @author YLY
 * @ClassName ABADemo
 * @Date 2020/4/30
 * @Version 1.0.2
 */
public class ABADemo {
    static AtomicReference<Integer> atomicReference = new AtomicReference<>(100);
    static AtomicStampedReference<Integer> atomicStampedReference = new AtomicStampedReference<>(100,1);
    public static void main(String[] args) {
        System.out.println("==============以下是ABA问题的产生=================");
        new Thread(()->{
            atomicReference.compareAndSet(100,101);
            atomicReference.compareAndSet(101,100);
        },"t1").start();

        new Thread(()->{
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(atomicReference.compareAndSet(100, 2019)+"\t"+atomicReference.get());
        },"t2").start();

        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("==============以下是ABA问题的解决=================");
        new Thread(()->{
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()+"\t第1次版本号："+stamp);
            //暂停1秒钟t3线程
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            atomicStampedReference.compareAndSet(100,101,atomicStampedReference.getStamp(),atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName()+"\t第2次版本号："+atomicStampedReference.getStamp());
            atomicStampedReference.compareAndSet(101,100,atomicStampedReference.getStamp(),atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName()+"\t第3次版本号："+atomicStampedReference.getStamp());
        },"t3").start();


        new Thread(()->{
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()+"\t第1次版本号："+stamp);
            //暂停3秒钟t4线程，保证上面的t3线程完成一次ABA操作
            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            boolean result = atomicStampedReference.compareAndSet(100, 2019, stamp, stamp + 1);
            System.out.println(Thread.currentThread().getName()+"\t修改成功与否："+result+"当前版本号为："+atomicStampedReference.getStamp());
            System.out.println(Thread.currentThread().getName()+"\t当前实际最新值为："+atomicStampedReference.getReference());
        },"t4").start();

    }
}
